AM GENERAL issued a recall on the HUMMER model

On certain vehicles, the nuts used to attach the master cylinder to the hydro-boost unit are of the metric type rather than the required English type. Although the English threaded bolts will accept the metric nuts, torque retention and clamping load of the nut-to-bolt joint is compromised. A loose master cylinder condition can occur, causing longer than normal brake pedal travel during brake pedal applications. Correction: Mounting bolts and nuts will be replaced with the correct compatible attachment hardware.